From 700ca40f6fc1addd7238f4ab57f76c095ad3c99f Mon Sep 17 00:00:00 2001 From: Jan Kratochvil Date: Wed, 15 Jul 2015 17:37:28 +0200 Subject: gdbserver build-id attribute generator Producer part of the new "build-id" XML attribute. gdb/ChangeLog 2015-07-15 Aleksandar Ristovski gdbserver build-id attribute generator. * features/library-list-svr4.dtd (library-list-svr4): New 'build-id' attribute. gdb/doc/ChangeLog 2015-07-15 Aleksandar Ristovski gdbserver build-id attribute generator. * gdb.texinfo (Library List Format for SVR4 Targets): Add 'build-id' in description, example, new attribute in dtd. gdb/gdbserver/ChangeLog 2015-07-15 Aleksandar Ristovski gdbserver build-id attribute generator. * linux-low.c (nat/linux-maps.h, search.h, rsp-low.h): Include. (ElfXX_Ehdr, ElfXX_Phdr, ElfXX_Nhdr): New. (ELFXX_FLD, ELFXX_SIZEOF, ELFXX_ROUNDUP, BUILD_ID_INVALID): New. (find_phdr): New. (get_dynamic): Use find_pdhr to traverse program headers. (struct mapping_entry, mapping_entry_s, free_mapping_entry_vec) (compare_mapping_entry_range, struct find_memory_region_callback_data) (read_build_id, find_memory_region_callback, lrfind_mapping_entry) (get_hex_build_id): New. (linux_qxfer_libraries_svr4): Add optional build-id attribute to reply XML document. --- gdb/gdbserver/ChangeLog | 16 ++ gdb/gdbserver/linux-low.c | 398 +++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 378 insertions(+), 36 deletions(-) (limited to 'gdb/gdbserver') diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog index f4896eb..af8c8d5 100644 --- a/gdb/gdbserver/ChangeLog +++ b/gdb/gdbserver/ChangeLog @@ -1,6 +1,22 @@ 2015-07-15 Aleksandar Ristovski + gdbserver build-id attribute generator. + * linux-low.c (nat/linux-maps.h, search.h, rsp-low.h): Include. + (ElfXX_Ehdr, ElfXX_Phdr, ElfXX_Nhdr): New. + (ELFXX_FLD, ELFXX_SIZEOF, ELFXX_ROUNDUP, BUILD_ID_INVALID): New. + (find_phdr): New. + (get_dynamic): Use find_pdhr to traverse program headers. + (struct mapping_entry, mapping_entry_s, free_mapping_entry_vec) + (compare_mapping_entry_range, struct find_memory_region_callback_data) + (read_build_id, find_memory_region_callback, lrfind_mapping_entry) + (get_hex_build_id): New. + (linux_qxfer_libraries_svr4): Add optional build-id attribute + to reply XML document. + +2015-07-15 Aleksandar Ristovski + * target.c: Include target/target-utils.h and fcntl.h. (target_fileio_read_stralloc_1_pread, target_fileio_read_stralloc_1) (target_fileio_read_stralloc): New functions. diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c index 2dafb03..eedd652 100644 --- a/gdb/gdbserver/linux-low.c +++ b/gdb/gdbserver/linux-low.c @@ -22,6 +22,7 @@ #include "agent.h" #include "tdesc.h" #include "rsp-low.h" +#include "nat/linux-maps.h" #include "nat/linux-nat.h" #include "nat/linux-waitpid.h" @@ -43,9 +44,11 @@ #include #include #include +#include #include "filestuff.h" #include "tracepoint.h" #include "hostio.h" +#include "rsp-low.h" #ifndef ELFMAG0 /* Don't include here. If it got included by gdb_proc_service.h then ELFMAG0 will have been defined. If it didn't get included by @@ -182,6 +185,31 @@ lwp_stop_reason (struct lwp_info *lwp) return lwp->stop_reason; } +typedef union ElfXX_Ehdr +{ + Elf32_Ehdr _32; + Elf64_Ehdr _64; +} ElfXX_Ehdr; + +typedef union ElfXX_Phdr +{ + Elf32_Phdr _32; + Elf64_Phdr _64; +} ElfXX_Phdr; + +typedef union ElfXX_Nhdr +{ + Elf32_Nhdr _32; + Elf64_Nhdr _64; +} ElfXX_Nhdr; + +#define ELFXX_FLD(elf64, hdr, fld) ((elf64) ? (hdr)._64.fld : (hdr)._32.fld) +#define ELFXX_SIZEOF(elf64, hdr) ((elf64) ? sizeof ((hdr)._64) \ + : sizeof ((hdr)._32)) +/* Round up to next 4 byte boundary. */ +#define ELFXX_ROUNDUP_4(elf64, what) (((what) + 3) & ~(ULONGEST) 3) +#define BUILD_ID_INVALID "?" + /* A list of all unknown processes which receive stop signals. Some other process will presumably claim each of these as forked children momentarily. */ @@ -6010,15 +6038,38 @@ get_phdr_phnum_from_proc_auxv (const int pid, const int is_elf64, return 0; } +/* Linearly traverse pheaders and look for P_TYPE pheader. */ + +static const void * +find_phdr (const int is_elf64, const void *const phdr_begin, + const void *const phdr_end, const ULONGEST p_type) +{ +#define PHDR_NEXT(hdrp) ((const void *) ((const gdb_byte *) (hdrp) + \ + ELFXX_SIZEOF (is_elf64, *hdrp))) + + const ElfXX_Phdr *phdr = phdr_begin; + + while (PHDR_NEXT (phdr) <= phdr_end) + { + if (ELFXX_FLD (is_elf64, *phdr, p_type) == p_type) + return phdr; + phdr = PHDR_NEXT (phdr); + } + + return NULL; +#undef PHDR_NEXT +} + /* Return &_DYNAMIC (via PT_DYNAMIC) in the inferior, or 0 if not present. */ static CORE_ADDR get_dynamic (const int pid, const int is_elf64) { CORE_ADDR phdr_memaddr, relocation; - int num_phdr, i; + int num_phdr; unsigned char *phdr_buf; - const int phdr_size = is_elf64 ? sizeof (Elf64_Phdr) : sizeof (Elf32_Phdr); + const ElfXX_Phdr *phdr; + const int phdr_size = ELFXX_SIZEOF (is_elf64, *phdr); if (get_phdr_phnum_from_proc_auxv (pid, is_elf64, &phdr_memaddr, &num_phdr)) return 0; @@ -6032,22 +6083,10 @@ get_dynamic (const int pid, const int is_elf64) /* Compute relocation: it is expected to be 0 for "regular" executables, non-zero for PIE ones. */ relocation = -1; - for (i = 0; relocation == -1 && i < num_phdr; i++) - if (is_elf64) - { - Elf64_Phdr *const p = (Elf64_Phdr *) (phdr_buf + i * phdr_size); - - if (p->p_type == PT_PHDR) - relocation = phdr_memaddr - p->p_vaddr; - } - else - { - Elf32_Phdr *const p = (Elf32_Phdr *) (phdr_buf + i * phdr_size); - - if (p->p_type == PT_PHDR) - relocation = phdr_memaddr - p->p_vaddr; - } - + phdr = find_phdr (is_elf64, phdr_buf, phdr_buf + num_phdr * phdr_size, + PT_PHDR); + if (phdr != NULL) + relocation = phdr_memaddr - ELFXX_FLD (is_elf64, *phdr, p_vaddr); if (relocation == -1) { /* PT_PHDR is optional, but necessary for PIE in general. Fortunately @@ -6063,23 +6102,11 @@ get_dynamic (const int pid, const int is_elf64) return 0; } - for (i = 0; i < num_phdr; i++) - { - if (is_elf64) - { - Elf64_Phdr *const p = (Elf64_Phdr *) (phdr_buf + i * phdr_size); - - if (p->p_type == PT_DYNAMIC) - return p->p_vaddr + relocation; - } - else - { - Elf32_Phdr *const p = (Elf32_Phdr *) (phdr_buf + i * phdr_size); + phdr = find_phdr (is_elf64, phdr_buf, phdr_buf + num_phdr * phdr_size, + PT_DYNAMIC); - if (p->p_type == PT_DYNAMIC) - return p->p_vaddr + relocation; - } - } + if (phdr != NULL) + return ELFXX_FLD (is_elf64, *phdr, p_vaddr) + relocation; return 0; } @@ -6219,6 +6246,278 @@ struct link_map_offsets int l_prev_offset; }; + +/* Structure for holding a mapping. Only mapping + containing l_ld can have hex_build_id set. */ + +struct mapping_entry +{ + /* Fields are populated from linux_find_memory_region parameters. */ + + ULONGEST vaddr; + ULONGEST size; + ULONGEST offset; + ULONGEST inode; + + /* Hex encoded string allocated using xmalloc, and + needs to be freed. It can be NULL. */ + + char *hex_build_id; +}; + +typedef struct mapping_entry mapping_entry_s; + +DEF_VEC_O(mapping_entry_s); + +/* Free vector of mapping_entry_s objects. */ + +static void +free_mapping_entry_vec (VEC (mapping_entry_s) *lst) +{ + int ix; + mapping_entry_s *p; + + for (ix = 0; VEC_iterate (mapping_entry_s, lst, ix, p); ++ix) + xfree (p->hex_build_id); + + VEC_free (mapping_entry_s, lst); +} + +/* Used for finding a mapping containing the given + l_ld passed in K. */ + +static int +compare_mapping_entry_range (const void *const k, const void *const b) +{ + const ULONGEST key = *(const CORE_ADDR *) k; + const mapping_entry_s *const p = b; + + if (key < p->vaddr) + return -1; + + if (key < p->vaddr + p->size) + return 0; + + return 1; +} + +struct find_memory_region_callback_data +{ + unsigned is_elf64; + + /* Return. Must be freed with free_mapping_entry_vec. */ + VEC (mapping_entry_s) *list; +}; + +/* Read build-id from PT_NOTE. + Argument LOAD_ADDR represents run time virtual address corresponding to + the beginning of the first loadable segment. L_ADDR is displacement + as supplied by the dynamic linker. */ + +static void +read_build_id (struct find_memory_region_callback_data *const p, + mapping_entry_s *const bil, const CORE_ADDR load_addr, + const CORE_ADDR l_addr) +{ + const int is_elf64 = p->is_elf64; + ElfXX_Ehdr ehdr; + + if (linux_read_memory (load_addr, (unsigned char *) &ehdr, + ELFXX_SIZEOF (is_elf64, ehdr)) == 0 + && ELFXX_FLD (is_elf64, ehdr, e_ident[EI_MAG0]) == ELFMAG0 + && ELFXX_FLD (is_elf64, ehdr, e_ident[EI_MAG1]) == ELFMAG1 + && ELFXX_FLD (is_elf64, ehdr, e_ident[EI_MAG2]) == ELFMAG2 + && ELFXX_FLD (is_elf64, ehdr, e_ident[EI_MAG3]) == ELFMAG3) + { + const ElfXX_Phdr *phdr; + void *phdr_buf; + const unsigned e_phentsize = ELFXX_FLD (is_elf64, ehdr, e_phentsize); + + if (ELFXX_FLD (is_elf64, ehdr, e_phnum) >= 100 + || e_phentsize != ELFXX_SIZEOF (is_elf64, *phdr)) + { + /* Basic sanity check failed. */ + warning (_("Could not identify program header at %s."), + paddress (load_addr)); + return; + } + + phdr_buf = alloca (ELFXX_FLD (is_elf64, ehdr, e_phnum) * e_phentsize); + + if (linux_read_memory (load_addr + ELFXX_FLD (is_elf64, ehdr, e_phoff), + phdr_buf, + ELFXX_FLD (is_elf64, ehdr, e_phnum) * e_phentsize) + != 0) + { + warning (_("Could not read program header at %s."), + paddress (load_addr)); + return; + } + + phdr = phdr_buf; + + for (;;) + { + gdb_byte *pt_note; + const gdb_byte *pt_end; + const ElfXX_Nhdr *nhdr; + CORE_ADDR note_addr; + + phdr = find_phdr (p->is_elf64, phdr, (gdb_byte *) phdr_buf + + ELFXX_FLD (is_elf64, ehdr, e_phnum) * e_phentsize, + PT_NOTE); + if (phdr == NULL) + break; + pt_note = xmalloc (ELFXX_FLD (is_elf64, *phdr, p_memsz)); + note_addr = ELFXX_FLD (is_elf64, *phdr, p_vaddr) + l_addr; + if (linux_read_memory (note_addr, pt_note, + ELFXX_FLD (is_elf64, *phdr, p_memsz)) != 0) + { + xfree (pt_note); + warning (_("Could not read note at address 0x%s"), + paddress (note_addr)); + break; + } + + pt_end = pt_note + ELFXX_FLD (is_elf64, *phdr, p_memsz); + nhdr = (void *) pt_note; + while ((const gdb_byte *) nhdr < pt_end) + { + const size_t namesz + = ELFXX_ROUNDUP_4 (is_elf64, ELFXX_FLD (is_elf64, *nhdr, + n_namesz)); + const size_t descsz + = ELFXX_ROUNDUP_4 (is_elf64, ELFXX_FLD (is_elf64, *nhdr, + n_descsz)); + const size_t note_sz = (ELFXX_SIZEOF (is_elf64, *nhdr) + namesz + + descsz); + + if (((const gdb_byte *) nhdr + note_sz) > pt_end || note_sz == 0 + || descsz == 0) + { + warning (_("Malformed PT_NOTE at address 0x%s\n"), + paddress (note_addr + (gdb_byte *) nhdr - pt_note)); + break; + } + if (ELFXX_FLD (is_elf64, *nhdr, n_type) == NT_GNU_BUILD_ID + && ELFXX_FLD (is_elf64, *nhdr, n_namesz) == 4) + { + const char gnu[4] = "GNU\0"; + const char *const pname + = (char *) nhdr + ELFXX_SIZEOF (is_elf64, *nhdr); + + if (memcmp (pname, gnu, 4) == 0) + { + const size_t n_descsz = ELFXX_FLD (is_elf64, *nhdr, + n_descsz); + + bil->hex_build_id = xmalloc (n_descsz * 2 + 1); + bin2hex ((const gdb_byte *) pname + namesz, + bil->hex_build_id, n_descsz); + xfree (pt_note); + return; + } + } + nhdr = (void *) ((gdb_byte *) nhdr + note_sz); + } + xfree (pt_note); + } + } +} + +static linux_find_memory_region_ftype find_memory_region_callback; + +/* Add mapping_entry. See linux_find_memory_ftype for the parameters + description. */ + +static int +find_memory_region_callback (ULONGEST vaddr, ULONGEST size, ULONGEST offset, + ULONGEST inode, int read, int write, int exec, + int modified, const char *filename, void *data) +{ + if (inode != 0) + { + struct find_memory_region_callback_data *const p = data; + mapping_entry_s bil; + + bil.vaddr = vaddr; + bil.size = size; + bil.offset = offset; + bil.inode = inode; + bil.hex_build_id = NULL; + + VEC_safe_push (mapping_entry_s, p->list, &bil); + } + + /* Continue the traversal. */ + return 0; +} + +/* Linear reverse find starting from RBEGIN towards REND looking for + the lowest vaddr mapping of the same inode and zero offset. */ + +static mapping_entry_s * +lrfind_mapping_entry (mapping_entry_s *const rbegin, + const mapping_entry_s *const rend) +{ + mapping_entry_s *p; + + for (p = rbegin - 1; p >= rend; --p) + if (p->offset == 0 && p->inode == rbegin->inode) + return p; + + return NULL; +} + +/* Get build-id for the given L_LD, where L_LD corresponds to + link_map.l_ld as specified by the dynamic linker. + DATA must point to already filled list of mapping_entry elements. + + If build-id had not been read, read it and cache in corresponding + list element. + + Return build_id as stored in the list element corresponding + to L_LD. + + NULL may be returned if build-id could not be fetched. + + Returned string must not be freed explicitly. */ + +static const char * +get_hex_build_id (const CORE_ADDR l_addr, const CORE_ADDR l_ld, + struct find_memory_region_callback_data *const data) +{ + mapping_entry_s *bil; + + bil = bsearch (&l_ld, VEC_address (mapping_entry_s, data->list), + VEC_length (mapping_entry_s, data->list), + sizeof (mapping_entry_s), compare_mapping_entry_range); + + if (bil == NULL) + return NULL; + + if (bil->hex_build_id == NULL) + { + mapping_entry_s *bil_min; + + bil_min = lrfind_mapping_entry (bil, VEC_address (mapping_entry_s, + data->list)); + if (bil_min != NULL) + read_build_id (data, bil, bil_min->vaddr, l_addr); + else + { + /* Do not try to find hex_build_id again. */ + bil->hex_build_id = xstrdup (BUILD_ID_INVALID); + warning (_("Could not determine load address; mapping entry with " + "offset 0 corresponding to l_ld = 0x%s could not be " + "found; build-id can not be used."), + paddress (l_ld)); + } + } + + return bil->hex_build_id; +} + /* Construct qXfer:libraries-svr4:read reply. */ static int @@ -6231,6 +6530,15 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf, struct process_info_private *const priv = current_process ()->priv; char filename[PATH_MAX]; int pid, is_elf64; + struct find_memory_region_callback_data data; + + /* COREFILTER_ANON_PRIVATE and COREFILTER_ANON_SHARED do not have an + associated file so it is not expected it could have an ELF header. */ + const enum filterflags filterflags = (COREFILTER_MAPPED_PRIVATE + | COREFILTER_MAPPED_SHARED + | COREFILTER_ELF_HEADERS + | COREFILTER_HUGETLB_PRIVATE + | COREFILTER_HUGETLB_SHARED); static const struct link_map_offsets lmo_32bit_offsets = { @@ -6273,6 +6581,14 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf, lmo = is_elf64 ? &lmo_64bit_offsets : &lmo_32bit_offsets; ptr_size = is_elf64 ? 8 : 4; + data.is_elf64 = is_elf64; + data.list = NULL; + VEC_reserve (mapping_entry_s, data.list, 16); + if (linux_find_memory_regions_full (pid, filterflags, + find_memory_region_callback, &data) + < 0) + warning (_("Finding memory regions failed")); + while (annex[0] != '\0') { const char *sep; @@ -6379,6 +6695,7 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf, /* 6x the size for xml_escape_text below. */ size_t len = 6 * strlen ((char *) libname); char *name; + const char *hex_enc_build_id = NULL; if (!header_done) { @@ -6387,7 +6704,11 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf, header_done = 1; } - while (allocated < p - document + len + 200) + hex_enc_build_id = get_hex_build_id (l_addr, l_ld, &data); + + while (allocated < (p - document + len + 200 + + (hex_enc_build_id != NULL + ? strlen (hex_enc_build_id) : 0))) { /* Expand to guarantee sufficient storage. */ uintptr_t document_len = p - document; @@ -6399,9 +6720,13 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf, name = xml_escape_text ((char *) libname); p += sprintf (p, "", + "l_addr=\"0x%lx\" l_ld=\"0x%lx\"", name, (unsigned long) lm_addr, (unsigned long) l_addr, (unsigned long) l_ld); + if (hex_enc_build_id != NULL + && strcmp (hex_enc_build_id, BUILD_ID_INVALID) != 0) + p += sprintf (p, " build-id=\"%s\"", hex_enc_build_id); + p += sprintf (p, "/>"); free (name); } } @@ -6428,6 +6753,7 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf, memcpy (readbuf, document + offset, len); xfree (document); + free_mapping_entry_vec (data.list); return len; } -- cgit v1.1